Experimental study and comprehensive analysis of leakage characteristics of the casing flange of an aero-engine

Leakage at the casing flange in aero-engines can reduce the engine performance and endanger the normal operation of the whole aircraft. An experimental system is designed in this paper to investigate the influence of loaded parameters and structural parameters on the sealing characteristics of the casing flange in aero-engines. The system includes an experimental table subsystem, a hydraulic subsystem, an inflation and leakage measurement subsystem and an experimental data acquisition subsystem. The results show that the gas pressure has a greater influence compared to the axial force. When the gas pressure rises from 0.2 MPa to 0.5 MPa, the leakage volume increases from about 9 L/min to about 34 L/min. Among the structural parameters, the number of bolts has the greatest influence, followed by the number of layers, and the surface roughness has the least influence, with the three influencing parameters not being mutually exclusive. The benefits of improving the structural parameters to reduce the leakage volume all increase with the rise of gas pressure. The leakage volume of experiment parts with 48 bolts arranged on the 2-layer casing flange with surface roughness 1.6 and 3.2 are taken as two sets of the contract type data and fitted by the nested Genetic Algorithm. The fitted results indicate that increase of surface roughness from 1.6 to 3.2 will result in an increase of 26 L/min in the leakage volume. The conclusions from the paper can provide guidance suggestions for the sealing design of the aero-engine casing.